<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    
    <style>
        h3{
            font-family: Arial, Helvetica, sans-serif;
            font-weight: 500;
            font-size: 100%;
            color: red;
        }
        span{
            color: rgba(50, 50, 50,0.2);
        }

        div{
            /* height: 50px; */
            border: 1px solid #ccc;
            line-height: 10px;
            font-style: italic;
        }
    </style>
<span>
    字体颜色
</span>
    <h3>
        字体设置
    </h3>

    <div>
        行号
    </div>


<span>

</span>


</body>
</html>